.TH std::basic_syncbuf 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::basic_syncbuf \- std::basic_syncbuf

.SH Synopsis
   Defined in header <syncstream>
   template<

       class CharT,
       class Traits = std::char_traits<CharT>,                         \fI(since C++20)\fP
       class Allocator = std::allocator<CharT>

   > class basic_syncbuf : public std::basic_streambuf<CharT, Traits>

   std::basic_syncbuf is a wrapper for a std::basic_streambuf (provided at construction
   time as a pointer). It accumulates output in its own internal buffer, and atomically
   transmits its entire contents to the wrapped buffer on destruction and when
   explicitly requested, so that they appear as a contiguous sequence of characters. It
   guarantees that there are no data races and no interleaving of characters sent to
   the wrapped buffer as long as all other outputs made to the same buffer are made
   through, possibly different, instances of std::basic_syncbuf.

   Typical implementation of std::basic_syncbuf holds a pointer to the wrapped
   std::basic_streambuf, a boolean flag indicating whether the buffer will transmit its
   contents to the wrapped buffer on sync (flush), a boolean flag indicating a pending
   flush when the policy is to not emit on sync, an internal buffer that uses Allocator
   (such as std::string), and a pointer to a mutex used to synchronize emit between
   multiple threads accessing the same wrapped stream buffer (these mutexes may be in a
   hash map with pointers to std::basic_streambuf objects used as keys).

   Like other streambuf classes, std::basic_syncbuf is normally only accessed through
   the corresponding stream, std::osyncstream, not directly.

   Several typedefs for common character types are provided:

   Defined in header <syncstream>
   Type          Definition
   std::syncbuf  std::basic_syncbuf<char>
   std::wsyncbuf std::basic_syncbuf<wchar_t>

.SH Member types

   Member type    Definition
   char_type      CharT
   traits_type    Traits; the program is ill-formed if Traits::char_type is not
                  CharT.
   int_type       Traits::int_type
   pos_type       Traits::pos_type
   off_type       Traits::off_type
   allocator_type Allocator
   streambuf_type std::basic_streambuf<CharT, Traits>

.SH Member functions

.SH Public member functions
   constructor      constructs a basic_syncbuf object
                    \fI(public member function)\fP
   operator=        assigns a basic_syncbuf object
                    \fI(public member function)\fP
   swap             swaps two basic_syncbuf objects
                    \fI(public member function)\fP
   destructor       destroys the basic_syncbuf and emits its internal buffer
                    \fI(public member function)\fP
                    atomically transmits the entire internal buffer to the wrapped
   emit             streambuf
                    \fI(public member function)\fP
   get_wrapped      retrieves the wrapped streambuf pointer
                    \fI(public member function)\fP
   get_allocator    retrieves the allocator used by this basic_syncbuf
                    \fI(public member function)\fP
   set_emit_on_sync changes the current emit-on-sync policy
                    \fI(public member function)\fP
.SH Protected member functions
                    either emits, or records a pending flush, depending on the current
   sync             emit-on-sync policy
                    \fI(public member function)\fP

.SH Non-member functions

   std::swap(std::basic_syncbuf) specializes the std::swap algorithm
   (C++20)                       \fI(function template)\fP

Inherited from std::basic_streambuf

.SH Member types

   Member type Definition
   char_type   CharT
   traits_type Traits; the program is ill-formed if Traits::char_type is not
               CharT.
   int_type    Traits::int_type
   pos_type    Traits::pos_type
   off_type    Traits::off_type

.SH Member functions

   destructor         destructs the basic_streambuf object
   \fB[virtual]\fP          \fI\fI(virtual public member function\fP of\fP
                      std::basic_streambuf<CharT,Traits>)
.SH Locales
                      invokes imbue()
   pubimbue           \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      obtains a copy of the associated locale
   getloc             \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

.SH Positioning
                      invokes setbuf()
   pubsetbuf          \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      invokes seekoff()
   pubseekoff         \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      invokes seekpos()
   pubseekpos         \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      invokes sync()
   pubsync            \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

.SH Get area
                      obtains the number of characters immediately available in the get
   in_avail           area
                      \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      advances the input sequence, then reads one character without
   snextc             advancing again
                      \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

   sbumpc             reads one character from the input sequence and advances the
   stossc             sequence
   (removed in C++17) \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      reads one character from the input sequence without advancing the
   sgetc              sequence
                      \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      invokes xsgetn()
   sgetn              \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

.SH Put area
                      writes one character to the put area and advances the next
   sputc              pointer
                      \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      invokes xsputn()
   sputn              \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

.SH Putback
                      puts one character back in the input sequence
   sputbackc          \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP

                      moves the next pointer in the input sequence back by one
   sungetc            \fI(public member function of std::basic_streambuf<CharT,Traits>)\fP


.SH Protected member functions

   constructor   constructs a basic_streambuf object
                 \fI(protected member function)\fP
   operator=     replaces a basic_streambuf object
   \fI(C++11)\fP       \fI(protected member function)\fP
   swap          swaps two basic_streambuf objects
   \fI(C++11)\fP       \fI(protected member function)\fP
.SH Locales
   imbue         changes the associated locale
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
.SH Positioning
   setbuf        replaces the buffer with user-defined array, if permitted
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
                 repositions the next pointer in the input sequence, output sequence,
   seekoff       or both, using relative addressing
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
                 repositions the next pointer in the input sequence, output sequence,
   seekpos       or both using absolute addressing
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
   sync          synchronizes the buffers with the associated character sequence
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
.SH Get area
                 obtains the number of characters available for input in the associated
   showmanyc     input sequence, if known
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
   underflow     reads characters from the associated input sequence to the get area
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
                 reads characters from the associated input sequence to the get area
   uflow         and advances the next pointer
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
   xsgetn        reads multiple characters from the input sequence
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
   eback         returns a pointer to the beginning, current character and the end of
   gptr          the get area
   egptr         \fI(protected member function)\fP
   gbump         advances the next pointer in the input sequence
                 \fI(protected member function)\fP
                 repositions the beginning, next, and end pointers of the input
   setg          sequence
                 \fI(protected member function)\fP
.SH Put area
   xsputn        writes multiple characters to the output sequence
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
   overflow      writes characters to the associated output sequence from the put area
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)
   pbase         returns a pointer to the beginning, current character and the end of
   pptr          the put area
   epptr         \fI(protected member function)\fP
   pbump         advances the next pointer of the output sequence
                 \fI(protected member function)\fP
                 repositions the beginning, next, and end pointers of the output
   setp          sequence
                 \fI(protected member function)\fP
.SH Putback
                 puts a character back into the input sequence, possibly modifying the
   pbackfail     input sequence
   \fB[virtual]\fP     \fI\fI(virtual protected member function\fP of\fP
                 std::basic_streambuf<CharT,Traits>)

.SH Notes

   Feature-test macro  Value    Std                        Feature
   __cpp_lib_syncbuf  201803L (C++20) Synchronized buffered ostream (std::syncbuf,
                                      std::osyncstream) and manipulators
